Microfluidic Systems for the Study of Vascular Networks

Mechanical forces are important regulators of cell biology in health and disease. Cells in the vascular system are subjected to fluid shear stress, cyclic stretch, and differential pressure and at the same time they receive multiple biochemical cues. All these factor into the integrated response of the tissue. A microfluidic bioreactor has been constructed to facilitate studies into the roles of both biophysical and biochemical factors on capillary morphogenesis. The deviceis made of PDMS, cured on an SU-8 patterned wafer. Then a scaffold material, collagen, is induced into a specific region of devices that was designed to keep its shape and properties. Cells are seeded via one flow channel on the surface of the scaffold and then subjected to controlled mechanical factors like surface shear and trans-endomechanical pressure, or biochemical angiogenic factors, inducing the formation of vascular sprouts that extend across the scaffold to a second flow channel.

With the bioreactor, cells on the scaffold form a confluent monolayer and generate sprouts. They show different responses and interactions with the scaffold, following the angiogenic factors, fluidic factors, surface characteristics and scaffold properties. Experiments are now underway to find the relations between cell responses and controlled factors. The developed system is the first system that can control biochemical and mechanical factors together, and it can be used for comparing the effects of angiogenic factors under controlled environment with enhanced view. It can also be applied to study the process of angiogenesis that entails the growth of vascular sprouts emanating from one endothelial surface and connecting with the other.